Method of and apparatus for forming tubular articles from laminated materials



April 24, 1951 D. E. HERVEY ET AL 2,549,819

METHOD OF AND APPARATUS FOR FORMING TUBULAR ARTICLES FROM LAMINATED MATERIALS Filed Oct. 31. 1945 2 Sheets-Sheet 1 I IN VENTORS flawdzEU/ervey fioer/ A! He may A1TD R N EYS Apnfi 24, 1951 D. E. HERVEY ET AL 2,549,819

METHOD OF AND APPARATUS FOR FORMING TUBULAR ARTICLES FROM LAMINATEDMATERIALS Filed Oct. 31, 1945 2 Sheets-Sheet 2 tau 4.

ATTCI RN EYE Patented Apr. 24, 1951 UNITED STATES OFFICE David E. .Herveyand-Robert J-Iemex, 0111 Fol-UN. C.

A;plilicatii'm LO ctDber P31, 1'945,-.-S;erialfNo. 25,766

This -invention relates to :an apparatus and method :of forming articles from plywood and laminated materials.

Heretofore tubes or tubing that have been formed :f-rom plywood have consisted of either one complete revolution of the 'ipl-ywood with the .twoedges 'butted up against each other or where several thicknesses of the plywood are joined together, each layer is'a separate -piece and .is bent around the precedingon-e and the surfaces are glued-together.

Hie surfaces of the respective pieces of this pldi method are not moved-'sidewise or lengthwise during the laying up process, and each piece i-of plywood applied requires .a sep ra s ayin l-D process.

. ibeth internal and external pressure is :used to Anebjeot of this invention-therefore is .to;pro-

vide a method for making tubing and other Farticles wherein one piece of plywoodor laminated material makes more than one complete revolu- .tion-and the face of one portion :of the ,piece of plywood is glued to theiace of another portion 40f the same piece.

.It is to :be understood that this structure when completed .need not .be circular in cross-section v.butcould .be any-number of-shapes or sizes made up 10f =manylong-itudinalsections.

In ,some instances when the method ;is em- .ployed the .plywood or laminated materialneeds to be lapped over on .itself only .a very short distance while in others the plywood or laminated materialpmay consist .of .several layers wrapped over upon themselves .'two,.three :or .more times.

One of the .Chie'f advantages of this invention is that,prefabricatedsheets whichdo not shrink f i.

or swell appreciably, whichareflat and freejromi buckles, which are strong and .not apt :to break,

in handling, which may .make use -.of .low grade and "low price materials, and which will often reduce other costs of construction, may .be made directly .into the finished product by .multiple wrapping and by drawing these wrappings tight .by turning one ,or both, the cover placed over :the

wrappings .or the core, :over whic-h the -=wrappings ;-are ior-med .and thereby providing -a substantial in carryingwoutithemethod:iorming thettub- 555 shownin the=drawings form the tubing.

In carrying out the method embodying the invention as shown 'in Figures .1 to 3 inclusive, wherteexact inside dimensions are desirable, the filywooder laminatedimaterial I0 afterit has had adhesive applied to one or both faces thereof -is wrapped .around a longitudinally split core l2 in a counter-clockwise manner until it is all wrapped son thetcore i2 and :upon itself .to provide .a bond between the surfaces. To provide :maximum retentionwof adhesive it should be wrapped loosely at first as EShOWl'l 'in'Fig-ure 2. .In order to provide abetteribondnandeliminate 'aHy'VOi-ds that might :occur in the wrapping process a longitudinally split .cover or outside sectional tubular casing 14 is positioned .on the outer surface of :the tplywood ltzand isgradually diminished in size, while .the coreaand material are continuously turned :in 1a:-counterclockwise or-clockwisemannenibymeans .ofithe-tighteners 1-5,:securedzto the casing M on the :iopposite -.su-r-faees of the .free longitudinal edges thereofland adjacent each end thereof :and the sections 1&8 and 200i the tubing 1H!- .are' con- :nected byhinges 22.. I

This action brings pressurertoxbear onthe entire outer surface of theply-wood I-D,causing the suriace-of-each wrapping thereof to move, slip p1 skid -with relation-to each other.

The cover-is rretained position until the ad- Juesive :is partiallyeracompletelyset during which time heat may be applieddirectly :to the mate-- rial means of :high irequency induction of an electrical current-bymeans not shown.

.Ineorder to decrease the time necessarygior ibhe adhesive .to bond thelayers, the cover and .the ,core may be termed as the two electrodes 'of ;-a high -sfregp-iency heating unit to heat and set the adhesive by induction. This apparatus .is mot 2,549,810 Y i f Where exact outside dimensions are required or desired the cover or casing I4 is adjusted to the desired dimensions, and the cover though shown tubular in cross section can assume any desired shape, is held in this position while the plywood. Ill or laminated material is internally expanded by means of an inflatable bag 24 which is placed interiorly of the longitudinally split core I2 and is inflated by means of the air valve 26, causing internal pressure on the plywood Ill rather than external pressure as previously described, as in the previous method, the internal pressure is retained until the adhesive is partially or completely set.

In carrying out the method shown in Figures 4 and 5, the apparatus 38 is employed. The apparatus comprises an elongated base 32 having vertical ends 34 and diametrically opposed supports 35 formed integral with the base relatively spaced with relation to each other and internallyof the ends 34.

The base 32 is provided with a raised platform portion 38 which is integral with the base having the depending sides it, the platform 38 is provided with grooves 42 transversely thereof to receive the dovetail blocks 44 slidably therein.

Secured to the blocks 44 by means of fasteners G are the semi-circular hollow sections 48 and 5 respectively which abut at their inner faces to provide the casing 52.

Mounted for sliding movement in the supports is the sectional mandrel 54, which is keyed together at the joint 56 by means of the key 58. Secured to the outer ends of the mandrel 54 by fasteners 68 are the wheels 62 by means of which the mandrel can be rotated the purpose of which will be later explained.

The platform is provided at its outer sides with diametrically opposed supports 64 which are adapted to threadably receive the pressure screws 68 which are controlled by the wheels 63. The mandrel is provided with circular grooves i5 adjacent to its ends in which the catch or latch 12 engages to retain the mandrel in position in the supports 36, and a second set of grooves 14 internally of the grooves 19 permit steam or other heating mediums to enter the mandrel 54 by means of the inlet pipes 16. A spring pressed slide valve i3 retains the heating medium within the mandrel 54. When it is desired to move the mandrel 54 longitudinally of the casing 52, the screws 85 are threaded into the threaded bores 32 in the ends of the mandrel by means of the wheels 84 secured thereto by pins 56. When the wheels 84 are rotated in the opposite direction the mandrel will be withdrawn from the casing 52. One of-the bores 82 is shown in the left side of Figure 4.-

When this apparatus is used the end of the plywood I0 is mounted in the longitudinal slot 88 in the mandrel 54, which is then turned to wrap the plywood around the mandrel 54, and the casing is moved to envelope the plywood by means of the pressure screws E5, and the sections of the casing 52 are closed until their inner faces approach or abut while at the same time the mandrel is turned again to wrap the plywood tightly then a heat medium is applied to the mandrel 54, by means of the inlet pipe I6 and to the casing sections 48 and by means of an inlet 90. Thus external pressure, heat and rotary movement of the mandrel is effected to bind the tubing into a unitary structure as previously described.

In Figure 6 a hollow tubular casing 92 is employed having a base 94 secured to a support 96 by means of fasteners 98. In this instance steam is admitted to the casing 92 by the inlet pipe I99 and an inflatable bag I92 is positioned within a core I94 on which the plywood I 9 is wrapped.

Thus heat and internal pressure is used in this method of forming the tubing.

In Figure 7 an inflatable bag I96 is employed with the structure previously described in Figures s and 5, and include the semi-circular hollowsections 48 and 59, pressure screws 66 and steam inlets 99, the other elements remaining as previously described.

Thus internal and external pressure is employed as well as heat.

Another method in forming the tubing is to employ the structure shown in Figures 1 to 3 and turn. the cover wh le the bag is being inflated, also both core and cover may be rotated in oppo ite direction. v

In order to reduce the size of the pieces of plywood or laminated mater al and to affect save ings in time labor and to accomplish different forms or thicker walls two or more pieces may be introduced into the apparatus when forming the tubing.

It is believed that the method of the invention and the manner in wh ch it is carried out will be apparent to those skilled in the art and it is to be understood that the forms of apparatus shown and described herein, are merely used for purposes ofillustrat on, since other apparatus may be employed to carry out the "method and the invention is only to be limited by the scope of the appended claims.

Having thus described the invention what is claimed as new and desired to be secured by Letters Patent is:

l. The method of forming a hollow integrally molded seamless member which comprises the steps of coating a sheet of material with adhesive on both faces thereof, attaching one edge of the sheet of material to a longitudinally split core, spirally wrapping the sheet of material loosely upon itself and about the core in sue.- cessive convolutio-ns in cont guous coextensive layers to form a substantially hollow member, enclosing the wrapped material and core in a longitudinally extending casing having a form of desired shape, anchoring the outermost edge of the sheet material to the casing, turning the core and the wrapped sheet of material while holding the casing stationary, applying pressure to the core uniformly againstthe internal surface of the same simultaneously with the turning of the core to expand the core whereby each layer is caused to move relative to adjacent layers and heating the assembled parts to set the adhes ve. j

2. The method of forming a hollow integrally moulded seamless member which comprises the steps of coating 'a sheet of material with ad.- hesive on both faces thereof, spirally wrapping the sheet of material loosely upon itself and about the core in successive convolutions in contiguous coextensive layers to formia's'u bstantially hollow member, enclosing the wrapped material and core in a longitudinally extending casing having a form of desired shape, applying pressure uniformly against the innermost layer of the wrapped member to internally expand the same against the casingwhereby each layer is caused to move relative to adjacent layers and heating the assembled parts to set the adhesive.

DAVID E. HERVEY. ROBERT W. HERVEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Kempton Nov. 12, 1918 Egerton Aug. 12, 1924 Lloyd Nov. 3, 1936 Miller June 20, 1944 Goldman et a1. June 11, 1946 Luth et a1 Sept. 3, 1946 Ilch Nov. 26, 1946 Snoke Dec. 28, 1948 

